512 Noble — Geology of the Grand Canyon, Arizona. 



fine-grained. It is cross-bedded and ripple-marked throu; 

 out. The shales of the alternating beds are very soft £ 

 weather out, leaving etched-out bands between the sandsto: 

 which are very conspicuous in the cliff-faces. On the unc 

 surface of each sandstone layer are beautifully preserved s 

 cracks. The shales are fine-grained, fissile, and argillaceous 

 The succession in this alternating series is as follows : 



No. Bed Thickness 



S. S.— Sh. cycle 



1. Sandstone- 4' 



2" 





2. Shale 3' if 



._ 8' 



3. S.S 2' 







4. Sh 3' 





5' . 



5. S. S 1' 







6. Sh 2' 





3' 



7. S.S 7' 







8. Sh.. ....10' 



6" 



17' 6" 



9. S.S 5' 







10. Sh 3' 





8' 



11. S.S... _- 6' 







12. Sh 2' 



6" 



8' 6" 



13. S.S 6' 







14. Sh 3' 



6" 



9' 6' 



15. S.S 6' 







16. Sh 3' 



6" 



.- 9' 6" 



17. S.S _. 7' 



6" 





18. Sh 4' 





11' 6" 



19. S.S 3' 



6" 





20. Sh.__ 



6" 



4' 



21. S.S 2' 







22. Sh r 





3' 



23. S.S 3'10" 





24. Sh 2' 



6" 



6' 4" 



25. S.S 2' 







26. Sh 6' 



6" 



8' 6" 



27. S.S.._ 3' 







28. Sh 4' 





7' 



Total, 109' 4" Ave., 7'10" 



k. Alternating, vermilion, arenaceous shale and sandstone. 



The sandstone is white, compact, and fine-grained. It 

 cross-bedded and ripple-marked throughout. The unc 

 surface of each sandstone layer is sun-cracked where it r< 

 upon the arenaceous shale. The shale is vermilion in co 

 soft, and very sandy. Sun-cracks occur throughout. 



The succession is as follows : 



